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Implementing DRV8313

VenkataSainath Ravikanti
Prodigy 160 points
Other Parts Discussed in Thread: DRV8313EVM, DRV8313

Hi All,

I'm Developing a product to drive the BLDC Fan using DRV8313. I bought DRV8313EVM and been exploring it for a while. i want to realize it on the product, but I've got some queries before i do that. Please clarify.

1) There is already inbuilt OCP in the device, therefore, i think, external IDC current sensing through a resistor is not necessary. Is it right?

2) Can I connect nFAULT to nRESET, means, if a fault occurs due to Over Current Protection feature or Over Temperature Protection feature or UVLO feature, the nFAULT goes LOW pulling down nRESET there by disabling the device outputs.Once the faults get cleared then nFAULT floats releasing nRESET there by allowing the device to output the required channels.

3) Can I keep SLEEP pin pulled up by a 47k to 3.3V ? 
    Or can I leave this pin floating?
   I do not want to use this feature at all as it is not required in my product.

4) Can we always keep the pins EN1,EN2 & EN3 pulled up by a 47k to 3.3V ?
    By this I would want to Enable all the PWM signals to IN1, IN2 & IN3. Is it possible?
 
Thanks in Advance. :)
  • 0
    TI__Mastermind 26065 points

    Hi, Ravikanti

    Some comments of your question here.

    1. DRV8313 only has an on-chip comparator not an OpAmp. Also, the OCP function of the device is to protect other than current feedback control. So we build external one to serve the current control.

    2.  It not recommended to do this way. nFAULT at OCP is already latched the device OFF at danger state. But connected to nRESET may cause the device recover from the abnormal condition and cause damage.

    3. We have 100k internal pull down of nSLEEP. So floating is not matching your purpose. If pull high, should use a small resistor such as 1k  to external 3.3V other than the V3P3OUT.

    4. The same as (3). 47k may be too big to the internal 100k pull down. Just connect the ENx to external 3.3V with small resistors.

    Thanks.

  • 0 in reply to Wilson Zuo
    Prodigy 160 points

    Hi Mr. Zuo,

    Thank you for your response. That clarified a lot. Now i'm clear and can go ahead. Thank you again.

  • 0 in reply to Wilson Zuo
    Prodigy 160 points

    4. pulled up EN1 with 1k to Ext.3.3V

        pulled up EN2 with 1k to Ext.3.3V

        pulled up EN3 with 1k to Ext.3.3V

    but the motor is not running. it is stopping after 3 jerks & the EVM gets disconnected.

    the same was happening after resetting it also.

    does this happen only in the EVM?

    will it work fine with another hardware having only the necessary s/w? 

  • 0 in reply to VenkataSainath Ravikanti
    TI__Expert 8885 points

    Ravikanti,

    Both EN1/2/3 and IN1/2/3, require to generate proper PWM output  signals to Motor for running in trapezidoal control algorithm. 

    Pulling EN1/En2/En3 continously high does not allow  switching off both FETs in individual legs when it is demaned by trap algorithm that's the reason motor is not running properly. EVM firware supports trap algorithm.

    Pulling EN1/En2/En3 continously high can work with Sinsuidal PWM such as used in FOC control becuase in this type of PWM, all the FETs in each 3-half bridges kept swithcing all the time.

    Best Regards

    Milan

  • 0 in reply to Milan Rajne
    Prodigy 160 points

    Hi Mr.Milan,

    I've incorporated all the modifications and they are successfully working. I did these on the EVM itself. Output is fine. Removed the COMPO connection. That was no problem.

    And verified that external IDC_Sense isn't useful for our purpose and inbuilt OCP is protecting. DRV8313 is very nicely designed controller. Thanks TI for such nice product's development.